Fuel injecting device for internal combustion engines



K. MOHR April 18, 1939.

3 Sheets-Sheet 1 Filed Feb. 2, 1937 r 313 u n 1.2 N// a 0, 8 5d de y M31 3 0 M 1D ,WJHVW X U I! -I r w w :z:

April 18, 1939. MQHR 2,155,098

FUEL INJECTING DEVICE FOR INTERNAL COMBUSTION ENGINES Filed Feb. 2, 19573 Sheets-Sheet 2 Fig. 2.

April 18, 1939. K. MOHR 2,155,098

FUEL INJECTING DEVICE FOR INTERNAL COMBUSTION ENGINES Filed Feb. 2, 19373 Sheets-Sheet 3 Aid/e1. Ma /2.

INVENTOR ATTORNEYJ Patented Apr. 18, 1939 FUEL INJEC'IING DEVICE FORINTERNAL COMBUSTION ENGINES Karl Mohr, Kiel, Germany, a'ssignor toFried.

Krupp Germaniawerft Aktiengesellschaft, Kicl- Gaarden, GermanyApplication February 2, 1937, Serial No. 123,583 In Germany February 7,1936 5 Claims;

The invention relates to a fuelinjecting device for internal combustionengines in which a freely movable diiferential piston is acted upon bythe compression pressure produced in the working cylinder of the engine.Such differential pistons consist of a large air piston and a. smallfuel pump piston which advantageously are arranged so as to be somewhatmovable relatively to one another in order that they may adjustthemselves in the correct position in case their guides should not beincorrect alinement. If now a controlling member, such as a regulatinglever attached to the differential piston, be hinged to the part of thepump piston outside of its guide in such a manner, that with certainpositions of the lever a lateral force is exerted upon the piston, thenthe danger occurs of the pump piston due to its lateral play at one endcanting against its guide at the other end and becoming seized. Thisoccurs with such pistons, which are not positively actuated,particularly at outer dead center; for, in this position the guidedportion of the piston is the shortest and the lever arm between thepoint of thrust of the lateral force and the guide sleeve is thelongest.

The invention has for its object to eliminate this danger to thereliability of operation of fuel injecting devices of the type outlinedhereinbefore and to afford a very suitable and reliable drive for a.valve which drive is derived from the differential piston; for, abreakdown of these important members of the engine would entail stoppingof the whole engine which would have very serious consequences, inparticular with ships.

According to the invention the single valve to be controlled in the fuelinjecting device and formed by a check valve simultaneously serving assuction and overflow valve, is actuated from the differential pistonthrough an angle lever adapted to rock on a fixed journal. In order toavoid noxious lateral pressures on the small pump piston, one leg of thelever on the drive side is hinged to the large air piston or to a partmounted thereon, while the other lever arm, which actuates the valve, isin the form of a cam. The regulation of the fuel quantity to be injectedtakes place in known manner by displacing the eccentrically disposedjournal of the lever.

In order that the invention may be clearly understood and readilycarried into effect, an embodiment and a further development of the sameare illustrated by way of example in the accompanying drawings, in whichFigure 1 is a longitudinal section oi a fuel injecting device accordingto the invention,

Figure 2 is a cross section on the line II-II of Figure 1,

Figure 3 is the general view of a fuel injecting device according to theinvention as applied to a multi-cylinder internal combustion engine, and

Figure 4 is another view of a fuel injecting device as applied to amulti-cylinder internal combustion engine.

Referring first to Figures 1 and 2, a denotes the two-part housing of afuel injecting device in which is lodged a differential pistoncomprising a large air piston b and a small fuel pump piston c disposedbelow the former. The air piston b is guided in a sleeve d which iscomposed of several parts and has inserted into it inwardly contractingpiston rings e. The fuel piston c is guided in a one-part sleeve 1. Thetop cover 9 of the device has attached to it a conduit h communicatingwith the compression chamber of a working cylinder of the engine,through which conduit the pressure acts upon the differential piston onthe downwardly directed pressure stroke of the latter. In the guidesleeve 1 of the fuel piston and in the bottom cover 2' carrying thissleeve are provided bores k and m, which bores intercommunicate andconnect the pump space n situated below the piston c with a space 0 intowhich opens the suction valve 9. A bore q issues from the space 0 andleads to the injection valve (not shown) The suction valve p is lodgedin an inclined position in the lower cover 1' of the housing and iscontrolled by an angle lever one leg of which forms a cam r, whilst theother leg s is bifurcated and is hinged to the diflerential piston insuch a manner, that it takes part in the reciprocating motion thereof.The two arms of the bifurcated lever arm s engage on opposite sides ofthe fuel piston c with longitudinal play in blocks t t respectively,mounted in holding rings v '0 welded to a sleeve u. The lower end ofsleeve u constitutes an abutment for two coiled springs 10 w and underthe action of these springs abuts by means of an inner flange 2: againstthe upper enlarged end of the piston c. In this manner the sphericallyconcave upper front surface of the piston c is kept in permanent contactwith a correspondingly shaped companion surface of a pressure piece 11supported by the air piston b,

a certain clearance being provided between the periphery of the piece 1and the opposite piston wall. The sleeve u is further guided on thecylindrical inner surface 01' the air piston b.

The particular advantage obtained by the construction hereinbeforedescribed resides in the fact that the lateral pressure exerted upon thedifferential piston and caused by the movement of the lever controllingthe suction valve is not transmitted to the fuel pump, but is perfectlykept away therefrom and is taken up by the sleeve u which to this endhas a sumcient extent of bearing surface against the air piston b. Theair piston b in its turn has a comparatively great diameter and isfirmly guided over its whole length so that any canting of this pistondue to the thrust of the angle lever is excluded. A satisfactory andreliable operation of the fuel pump 0 is ensured further by the factthat its upper end is in permanent contact with the air piston, so thatthe two pistons do not lift from and violently strike against oneanother, but nevertheless owing to the positive contact of the twopiston parts on the spherical surface the fuel piston can be slightlydisplaced if the guides of the two pistons be not in correct alinement.In addition, the guide sleeve f of the fuel piston can be made verylong, since it is not in the way of the angle lever r, s.

Furthermore, a simplification is achieved by the described arrangement,when compared with known devices of this type, which resides in the factthat only one single bore opens into the pump space, through which thefuel is sucked, forced back and injected. The fuel quantity to beinjected is adjusted by the hand regulating device or by the governor ofthe engine by turning a shaft 2 between the two limit positions 1 and 2(full load and stop). This shaft 2 has eccentrically mounted on it theangle lever r, s. The cam r releases the suction valve sooner or lateron the downward stroke of the differential piston according to itseccentric position, so that the suction valve can close under the actionof the fuel pressure. The regulation may be such that on full load thesuction valve is already closed at the beginning of the pressure stroke,so that the largest fuel quantity to be injected is equal to the strokevolume of the fuel piston formed between its upper dead center and theposition in which the bore k is closed, see Figure 1. After theinjection is terminated, the freely movable piston b, c is elasticallybraked in known manner by the fuel still enclosed in the pump space.

The springs w, w are so determined as to be capable of not only securingthe correct contact between the piston b and piston c, but also ofreliably lifting the whole differential piston b, c on its fillingstroke up to its stop formed by the upper cover, under certainconditions together with the fuel present under a certain overpressurein the pump space.

In order to prevent transmission of lateral pressure by friction to thestem of the suction valve 1), during the motion of the angle lever 1', sa flat spring a is interposed between the cam r and the stem of valve p.One end of the spring a is fixed in such a position that the spring inall positions of the angle lever abuts with a slight initial pressureagainst the contact surface of the cam r. In this way any lifting of thespring from the cam is avoided. In addition, the spring a also takeselastically up the shocks of the head of the valve stem, which shocksotherwise would very soon cause wear of the exactly shaped curvedsurface of the cam.

With multi-cylinder internal combustion engines it is frequentlyimpossible to mount the eccentric shaft 2, which is to be turned by thegovernor or the hand mechanism in order to vary the fuel quantity, sothat it extends along the whole length of the engine in the position ofthe shaft 2 in Fig. 1. This difilculty arises particularly in thereconstruction of enginesin which the arrangement of the individualinjecting devices depends upon the given conditions of space.

In order to provide the possibility of applying the above-describedcontrolling mechanism also to such engines, the invention provides afurther development of the arrangement described, in so far as the anglelevers of the individual injecting devices of a multi-cylinder engineare mounted on individual short eccentric shafts which, in order to varythe fuel quantity .to be fed, can

be turned from a control shaft common to the whole engine, by means ofsystems of levers adapted to be adjusted independently of one another.Figure 3 is a side elevation of the parts under consideration of aninjecting device of this type.

a denotes again the housing of the device. The freely movabledifferential piston (not visible) operating in the housing a is actedupon at its upper front end by the compression pressure of the workingcylinder. The fuel fed to the device is supplied to the pump space bythe suction valve p provided in the lower cover 2' of the housing. Fromthe pump space also leads a pressure duct to the injection valve.

On the shaft 2 is eccentrically mounted an angle lever one arm s ofwhich is linked to the differential piston while the other arm r forms acam and controls the opening stroke of the suction valve.

For every fuel-injecting device of the internal combustion engine isprovided, according to the number of the working cylinders, anindividual shaft 2 as to the rest, the arrangement is the same as in theembodiment described and illustrated in Figures 1 and 2. The turningmovement of the eccentric shafts z required to vary the fuel quantitybetween the limit positions 1 and 2, that is Full load and Stop, iseffected through a system of levers b, c, 11' attached to every shaft 2and actuated by a control shaft e which is under the influence of thegovernor or the hand regulating mechanism.

The described arrangement makes it possible to apply an injecting devicecomprising the new controlling mechanism also in cases where nothrough-going shaft can be mounted immediately beside the controllingmechanisms. The control shaft e is arranged anywhere at a suitable placeindependently of the location of the injecting device.

The required correct play between the cam r and the stem of the suctionvalve is set by slightly turning the eccentric shaft 2 by means of aturnbuckle inserted in the link 0'. The angle through which theeccentric shaft is turned has to be determined therefore to be somewhatgreater than required for the two limit positions of the regulation ofthe fuel quantity to be fed. Every individual injecting device can thusbe adjusted independently in such manner as is required in assemblingthe parts, and every injecting device can be re-adjusted at any timeduring service in case of wear on the suction valve. No dismantling orre-flnishing of any parts is necessary in such cases, which is of greatimportance with ships on the high seas.

What I claim and desire to secure by Letters Patent is:

1. In a fuel injecting device for internal combustion engines, a freelymovable differential pis- 2. In a fuel injecting device for internalcombustion engines, a freely movable differential piston comprising alarge end and a small end, said large end being composed of two partsbetween which an enlarged portion of the small end of said differentialpiston is clamped in a way permitting a limited relative movement of thetwo ends of said piston, cylinders for the respective ends of saidpiston, means forming a fuel inlet conduit to the cylinder space inwhich the small end of said piston operates, a fuel inlet valvecontrolling said conduit, and a pivoted control member for said valvecomprising a lever arm linked to one of the parts of the large end ofsaid differential piston.

3.- In a fuel injecting device for internal combustion engines, a freelymovable differential piston comprising a large end and a small end,cylinders for the respective ends of said pistons,

said small end having an enlarged portion adiacent the large end of saidpiston, said large end comprising two relatively slidable parts betweenwhich the enlarged portion of said small end is clamped in a waypermitting a limited relative movement of the two ends of said piston,one part of said large end having a bell-shaped sleeve adapted to passover the cylinder in which the small end of said piston operates duringthe movement of said piston, means forming a fuel inlet conduit to thecylinder space in which the small end of said piston operates, a fuelinlet valve controlling said conduit, and a pivoted control member forsaid valve comprising a lever arm linked to said bell-shaped sleeve.

4. In a fuel injecting device for internal com bustion engines, a freelymovable differential piston comprising a large end and a small end, saidends being relatively movable, cylinders for the respective ends of saidpiston, means forming a fuel inlet conduit to the cylinder space inwhich the small end of said piston operates, a reciprocatlng' fuel inletvalve controlling said conduit, and a pivoted control member for saidvalve comprising a lever arm linked to the large end of saiddifferential piston and a cam coacting with said valve, and a flatspring inserted between said cam and said valve, said spring beinganchored to a stationary support and disposed approximately normal tothe axis of said valve.

5. In a fuel inlectingdevice for multicylinder internal combustionengines, a plurality of freely movable differential pistons eachcomprising a large end and a small end, said ends being relativelymovable, cylinders for the respective ends of said pistons, meansforming fuel inlet conduits to the respective cylinder spaces in whichthe small ends of said pistons operate, fuel inlet valves controllingthe respective conduits, a control member for each valve each comprisinga lever arm linked to the large end of the differential piston to whichit appertains, individual eccentric pivots for the respective controlmembers, a common control shaft for all of said pivots, and adjustabledevices individually connecting said pivots to said control shaft,whereby said pivots can be rocked simultaneously by said control shaft.

KARL MOI-IR.

